1. Field of the Invention
The present invention relates to an intraoral orthopedic appliance to align the mandible and maxilla for treatment of temporomandibular joint disorders.
2. General Discussion of the Background
Mandibular retrognathia is a common cause of temporomandibular joint disorders. In this condition, a misalignment of the mandible and maxilla forces the mandible backwards into the temporomandibular joint and causes a mechanical strain which can result in dislocation of the joint or degeneration of the muscles protecting the joint. Other symptoms include tenderness in the muscles or mastication, jaw opening limitation, clicking or popping sounds in the joint, disruption of the head posture mechanism, and aggravation of middle and inner ear conditions including dizziness, tinnitus, and eustachian tube blockage.
Orthodontists have long sought a device for realigning the mandible and maxilla. An early such device was the Herbst appliance, which is shown in German Patent No. 374,163. A metal band of the Herbst appliance was placed around an upper molar and a lower incisor tooth. These two bands were interconnected by a telescopic member to exert an anteriorly directed force on the lower jar, which eventually brought the lower jaw into alignment with the upper jaw. The Herbst appliance, however, inhibited lateral movement of the jaw and it needed great strength to resist breakage from lateral jaw forces, therefore it was bulky and interfered with speaking, eating and other oral activities.
Similar telescopic devices include those shown in U.S. Pat. Nos. 3,618,214; 4,472,138; and 4,462,800, as Well as French Patent No. 1,079,955. None of these dental appliances permitted lateral jaw movement, and they all required wires or braces to attach the device to a patient's teeth. Moreover, none of these devices were suitable for treating internally deranged temporomandibular joints in which the precise position of the mandible must be easily adjustable and must, in many cases, be able to be very gradually retruded from an extremely protruded position. Such gradual return to a more normal and comfortable jaw position is important, because any sudden retrusive shift can cause redisplacement of a recaptured displaced disc.
U.S. Pat. No. 4,382,783 did disclose a telescopic, intraoral orthodontic device which could be lengthened in very fine increments to realign the mandible and maxilla. This device, however, did not permit lateral jaw action and required placement of braces or bands on the teeth for attachment.
More recently, U.S. Pat. No. 4,618,324 disclosed a telescopic orthodontic device which was attached to upper and lower molars by a pair of opposing circular bands. The telescopic portion of the device was offset laterally from the teeth and toward the inner buccal surface to avoid interference with tooth movements. Pivotal connections between the bands and telescopic device also allowed transverse movement of the jaws without damaging the orthodontic appliance. In spite of these advantages, the appliance still placed excessive strain on the individual teeth to which it was attached, leading to tooth damage or fracture. Moreover, the lateral displacement of the device from the dental arches rubbed the inner buccal surfaces and was uncomfortable.
It is accordingly an object of the present invention to provide an improved intraoral orthopedic device for aligning the mandible and maxilla.